Hi,
We have a custom board on which ADS1299 is used to read the analog signals. Chip is connected to STM32 microcontroller. Following are the configurations we have done -
1. Sampling rate - 250SPS
2. ADS1299 master Clock - Internal (Also connected 2.048MHz crystal on CLK pin for external clock)
3. SPI Clock - 2.62 MHz
4. GPIO Pins - PWDN (Bar), START, DAISY_IN, RESET(Bar), DRDY(Bar), CLKSEL, CLK and SPI related pins.
Adding a code snippet of configuration -
HAL_GPIO_WritePin(GPIOD, ADS_RSTn_PD12_Pin, GPIO_PIN_SET);
HAL_Delay(100);
HAL_GPIO_WritePin(GPIOD, ADS_DAISY_IN_PD11_Pin, GPIO_PIN_RESET);
ADS1299_Master_Clock_Select(Internal_Clock); // Selected internal clock by pulling CLKSEL pin HIGH.
//ADS1299_Master_Clock_Select(External_Clock);
POWERUP_ADS1299(); // Sets PWDN (Bar) pin HIGH
HAL_Delay(128); //128ms of delay
RESET_ADS1299(); // 1ms reset pulse is provided
SDATAC(); // SDATAC command send
After this, we write register settings and then starts conversion by pulling START pin HIGH and sent RDATAC command.
We find following observations -
1. After conversion starts microcontroller receives the DRDY(Bar) signal for certain period of time and after that signal stops (Also observed on oscilloscope).
2. When we switched to external clock, microcontroller receives signal every time. (We are not sure this works for repetitive testing)
We want to know why DRDY (Bar) signal is not generating when internal clock used? or is there anything we are missing in configurations.
